Microbial detoxification of eleven food and feed contaminating trichothecene mycotoxins
Rafiq Ahad, Ting Zhou, Dion Lepp and K. Peter Pauls. 2017. Microbial detoxification of eleven food and feed contaminating trichothecene mycotoxins. BMC Biotechnology. DOI 10.1186/s12896-017-0352-7
Plain language summary
Contamination of agricultural commodities with multiple toxins produced by fungi (mycotoxins) is a serious food safety issue. A group of mycotoxins called trichothecene is mainly produced in grains including wheat, barley and corn by plant pathogens belonging to fungal genus, Fusarium. The contaminations of such mycotoxins significantly affect grain production and marketing values. Exposure to multiple trichothecene mycotoxins may even increase toxicity in animals due to their synergistic and/or additive effects. This study developed a novel means to address the problem by detoxifying various food and feed contaminating mycotoxins biologically under aerobic and anaerobic conditions and wide range of temperatures. A mixture of microorganisms named DX100 obtained from an enriched soil sample was found to be capable of changing the chemical structures of the toxins, converting eleven trichothecene mycotoxins into relative chemicals but significantly less toxic than the original mycotoxins. DX100 contains 70% known and 30% unknown bacterial species, dominated by Stenotrophomonas species. DX100 showed a rapid activity in converting mycotoxins into less toxic substances, e.g. Deoxynivalenol (DON) was completely converted into its non-toxic form, deep-DON within 48 h of incubation. DX100 represents a unique enzymatic source which has great industrial potential for reducing contamination of foods/feeds with multiple trichothecene mycotoxins and minimizing their synergistic/additive cytotoxic effects on animal and human health.
© 2017 The Author(s). Background: Contamination of agricultural commodities with multiple trichothecene mycotoxins, produced by toxigenic Fusarium species, is a food safety issue, which greatly affects grain production and marketing worldwide. Importantly, exposure to multiple trichothecenes may increase toxicity in animals due to their synergistic and/or additive effects. To address the problem this study aimed to achieve a novel biological trait capable of detoxifying various food and feed contaminating trichothecenes under aerobic and anaerobic conditions and wide range of temperatures. Results: A highly enriched microbial consortium (called DX100) capable of transforming eleven trichothecenes to significantly less toxic de-epoxy forms was achieved after prolonged incubation of soil microbial culture with 200 μg/mL deoxynivalenol (DON). DX100 demonstrated de-epoxidation activity under aerobic and anaerobic conditions, a greater range of temperatures and around neutral pH. The consortium contains 70% known and 30% unknown bacterial species, dominated by Stenotrophomonas species. Probably novel bacteria including strains of Stenotrophomonas and Alkaliphilus-Blautia species complex could be involved in aerobic and anaerobic de-epoxidation of trichothecenes, respectively. DX100 showed rapid and stable activity by de-epoxidizing 100% of 50 μg/mL deoxynivalenol at 48 h of incubation and retaining de-epoxidation ability after 100 subcultures in mineral salts broth (MSB). It was able to de-epoxidize high concentration of DON (500 μg/mL), and transformed ten more food contaminating trichothecenes into de-epoxy forms and/or other known/unknown compounds. Microbial de-epoxidation rate increased with increasing trichothecene concentrations in the broth media, suggesting that DX100 maintains a robust trichothecene detoxifying mechanism. Furthermore, the nature of microbial de-epoxidation reaction and inhibition of the reaction by sodium azide and the finding that bacterial cell culture lysate retained activity suggests that certain cytoplasmic reductases may be responsible for the de-epoxidation activity. Conclusions: This study reports the enrichment procedure for obtaining an effective and stable microbial consortium DX100 capable of de-epoxidizing several food contaminating trichothecene mycotoxins. DX100, which has de-epoxidation ability under wide range of conditions, represents a unique enzymatic source which has great industrial potential for reducing contamination of foods/feeds with multiple trichothecenes, and minimizing their synergistic/additive cytotoxic effects on consumer health.